The purpose of the proposed research is to study the relationship between the representation of time, space, and number and how language affects interactions between these representations. An important question is whether abstract concepts like number or time, are reasoned about by mapping them onto concrete structures such as space. There is some evidence that number is mapped onto space (Dehaene et al, 1993) and also that space is used to think about time (Boroditsky, 2000;Casasanto, 2007). It is unclear however, how these cross-domain mappings develop and whether language is a critical factor in their emergence. To explore these issues, I propose to test rhesus monkeys, 8 month old infants, and adult humans using a bisection procedure that examines how an irrelevant dimension influences decisions about another task-relevant dimension. Participants will first be trained to classify "large" and "small" anchor values for a given dimension (e.g. space, time, or number). Subsequently, participants will be given probe trials in which they will classify intermediate values as belonging to the "large" or "small" category. We will then determine the point of subjective equality (PSE) in which participants are equally likely to classify the stimulus as the "large" or "small". Next, we will conduct a cross-dimensional bisection test in which an irrelevant dimension is varied (e.g. space) while participants make bisection judgments about a relevant dimension (e.g. time). The purpose is to determine whether the values of the irrelevant dimension influence judgments of the relevant dimension, and secondly, whether dimensions influence each other symmetrically or asymmetrically (e.g. does space influence time judgments more than time influences space judgments?). These experiments will shed light on the development of abstract thinking in humans, and also help clarify the foundational roles of language and perceptual processes in the representation of time and number. Given previous research showing links between disruptions in spatial and numerical processing, our research may have implications for the development of some numerical processing disorders and dyscalculia. Prior research (demonstrates clear links between disruptions in spatial processing and disruptions in numerical processing (Zorzi et al, 2002).Understanding the links between space, time, and number, and how these representations develop, may help explain the relationship between disruptions in spatial processing and other cognitive abilities. This research may therefore provide theoretical groundwork for clinical behavioral screens for complexes of learning difficulties that may be associated with mappings between number, space, and time.